The World Health Organization says it has extended a nationwide polio vaccination campaign due to difficulties in accessing children.
It says vaccinators struggle to find every child from the displaced families scattered in area that are hard to reach.
The campaign started on the 15th of this month and was expected to continue until last Friday.
But WHO said insecurity, ongoing clashes and displacement made the logistical arrangements overwhelming, leading to the extension for another four days until tomorrow.
In a statement, the UN agency says despite insecurity in some parts of the country, it is still targeting more than 3.5 million children below five years.
“The achievement of this successful campaign brings hope to the humanitarian community,” said the WHO Representative to South Sudan, Dr Abdulmumini Usman.
“The commitment of health teams to reach as many children as possible in difficult circumstances is really to be commended”.
The WHO says it has already reached an estimated 1.1 million children with oral polio vaccines in collaboration with partners.
The campaign is using both house-to-house and facility-based services to reach all children regardless of their location.
The polio vaccination campaign was organized and led by the Ministry of Health with support from WHO and UNICEF.
Polio is a disease that cripples children. It can be prevented through vaccination.